A water-discoloring toy has been disclosed which comprises a substrate and, formed thereon, a porous layer which comprises a binder resin and a low-refractive-index pigment fixed therein in a dispersed state and has a difference in transparency between a liquid-impregnated state and an unimpregnated state (U.S. Pat. No. 6,953,345).
In this prior-art sheet, the lower layer is hidden when the porous layer is in a dry state (unimpregnated state), and this porous layer can be transparentized by impregnating the layer with a liquid, e.g., water, to produce an image having the color tone of the lower layer. However, images obtained in this manner are limited to ones having a single color tone. Even though the sheet can be repeatedly used, images which can be produced are reproductions of the image. The prior-art sheet has hence been unsatisfactory in unexpectedness and niceties of change.